Honda Motor Co Ltd has high hopes for its hydrogen fuel cell vehicle and its advanced technology to reduce tailpipe emissions, although the Japanese carmaker concedes consumers may take a few years to warm to the concept.

Honda unveiled the 5-passenger vehicle at the Los Angeles Auto Show on Wednesday. It doesn't have a name, for now, and is referred to simply by the acronym for a fuel cell electric vehicle - the 'FCEV Concept'.

The fuel cell vehicle is expected to launch in the United States and Japan in 2015, but the odds are the car won't make an appearance in most US showrooms until well beyond that year.

Adoption of hydrogen fuel cell vehicles has been stunted by their high price and a lack of investment in fueling infrastructure. There are currently just 10 public hydrogen fueling stations in the United States, according to the US Department of Energy.

"The beginning of the launch, the timing of 2015, I don't think we will have a big volume," Tetsuo Iwamura, chief executive of Honda's US business, told reporters at the Los Angeles Auto Show. Higher volumes will come gradually, he said.

Honda did not say how much it expects the vehicle to cost.

"This type of technology can't happen immediately across the US," he added, saying adoption of fuel cell vehicles would likely begin to grow in small markets like Southern California.

Carlos Ghosn, the CEO of Renault SA and Nissan Motor Co, echoed Iwamura's concerns at the Tokyo Motor Show on Wednesday, saying infrastructure costs could stall the uptake of fuel cell cars.

California aims to have 1.5 million zero-emissions vehicles, which would include fuel cell cars, on its roads by 2025.

Fuel-cell cars use a "stack" of cells that combine hydrogen with oxygen in the air to generate electricity. Their only emission is water vapor and they can run five times longer than electric cars.

Fuel cells are much less of a burden on the environment than rival technologies, Iwamura said when asked why Honda was investing in a technology that lacks a refueling infrastructure.

Honda and General Motors Co in July said they would jointly develop hydrogen fuel-cell vehicle systems over the next seven years in an effort to cut the cost of the new technology.

There are just two fuel-cell vehicles available in the US market: Honda's FCX Clarity, which is available to lease, and the Mercedes-Benz F-Cell.